Different factors possibly involved in post-translational regulation of ornithine decarboxylase activity.

Present results concern a microsome-bound enzymatic system which has been recognized as responsible for the rapid inactivation in vitro of ornithine decarboxylase (ODC). Two different models have been investigated: a) rat liver after a single thioacetamide administration, and b) the 3924 A Morris hepatoma. In both these models we observed variations in the microsome-bound ODC-inactivating capacity. In parallel, changes in ODC properties were observed. The possibility of a causal relationship between the two events is discussed. The actual role of the microsome-bound ODC-inactivating system, in ODC activity regulation in vivo cannot be established, but it remains as a fairly plausible working hypothesis.